The brittle star genome illuminates the genetic basis of animal appendage regeneration

Abstract

Species within nearly all extant animal lineages are capable of regenerating body parts. However, it remains unclear whether the gene expression programme controlling regeneration is evolutionarily conserved. Brittle stars are a species-rich class of echinoderms with outstanding regenerative abilities, but investigations into the genetic bases of regeneration in this group have been hindered by the limited genomic resources. Here, we report a chromosome-scale genome assembly for the brittle starAmphiura filiformis.We show that the brittle star genome is the most rearranged amongst echinoderms sequenced to date, featuring a reorganised Hox cluster reminiscent of the rearrangements observed in sea urchins. In addition, we performed an extensive profiling of gene expression during brittle star adult arm regeneration and identified sequential waves of gene expression governing wound healing, proliferation and differentiation. We conducted comparative transcriptomic analyses with other invertebrate and vertebrate models for appendage regeneration and uncovered hundreds of genes with conserved expression dynamics, particularly during the proliferative phase of regeneration. Our findings emphasise the crucial importance of echinoderms to detect long-range expression conservation between vertebrates and classical invertebrate regeneration model systems.

A brittle star is born: Ontogeny of luminous capabilities in Amphiura filiformis

“…Most of the ophiuroids have a complex life history cycle alternating an adult benthic phase and a planktonic larval stage. A. filiformis is used as a model species around the world to study, among others, the extraordinary regenerative capabilities in echinoderms, for example, the recent release A. filiformis genome [30]. Moreover, this brittle star can be cultured in the laboratory throughout its life cycle [31,32].…”